Plotting lines between data points on a graph - PROBLEM!

im facing a problem of plotting a line between points plotted on a graph. below is my code. only points appear but not the line connected them. Why is this so? This code is within a FOR loop, is that why it doesnt work?

if ((cx>=10)&(cx<=60)&(cy>=10)&(cy<=60))    
    figure(2);
    title('Graphical Results');
    hold on;
    plot(j, diameter(j), 'ro-', 'LineWidth', 2, 'MarkerEdgeColor', 'k', 'MarkerFaceColor', 'g', 'MarkerSize', 10)
    ylabel('Diameter of pupil');
    xlabel('Frame');
    hold off;   
    set(gcf, 'Position', get(0, 'ScreenSize'));
    fprintf(1,'#%3d %11.1f %8.1f\n', j, diameter(j), area);     
    end

below is the graph i am getting...

http://i241.photobucket.com/albums/ff200/whu_esle/graphnotconnecting.png

you realised there isnt a line connected it.. i have tried many combinations but nothing works.

Answer 1

[Walter Roberson]

Unless you supply at least two X and two Y coordinates to plot(), all it can do is draw the one point you give it.

You would be better off storing the j values until the end of the loop, and then

plot(Jlist, diameter(Jlist), 'ro-' <etc>)